3 Main Ideas How did Mendeleev organize his periodic table?How is current periodic table organized?What is eka-aluminum? Gallium?What does it mean if something is “periodic?”What information can we learn from periods? Groups?What are the characteristics of metals, nonmetals, and metalloids?What determines how reactive an element is?What is the most reactive metal? Nonmetal?Why are the noble gases so unreactive?

4 Let’s PracticeAnswer the following questions using your periodic table.How many valence electrons does an atom of chlorine have? Bromine? Iodine?How many energy levels does an atom of lead have?Is strontium a metal or nonmetal? What state of matter is it?How many naturally occurring elements are there?